This application is in response to the NINDS's request for applications for Clinical Sites to complete the performance of ongoing NET-PD studies. The NET-PD infrastructure, comprising a Clinical Coordinating Center, a Statistical Center, and multiple clinical sites has conducted multiple futility trials and is currently conductng a phase 111 clinical trial evaluating creatine compared with placebo in over 1700 patients. Enrollment in the creatine trial (LS-1) was completed in 2010, with follow-up expected to be completed in 2015, when the last patient enrolled reaches 5 years of follow-up. The objective of the current solicitations to maintain the NET-PD network by supporting Clinical Sites capable of continuing all patient follow-up activities necessary for the successful completion of LS-1. Parkinson's disease (PD) currently affects at least a half million Americans. Available pharmacotherapies are usually effective for controlling symptoms during the initial years after diagnosis; however, disease progression leads to the need for higher doses of multiple medications with increasing side-effects and decreasing benefits. Although these treatments can dramatically improve the lives of patients with Parkinson's disease initially, current agents do not address the underlying cause of the disease or its relentless progression. Effective clinical neuroprotection would substantially reduce PD-related disability for hundreds of thousands of Americans. Therefore, NINDS initiated the NET-PD program to conduct clinical trials aimed at evaluating the neuroprotective potential of pharmacological agents designed to slow the progression of PD. The goal of this initiative is to provide continuing Clinical Site support for the completion of the current ongoing clinical trials being conducted in the NET-PD network. For the LS-1 study, new subjects are no longer being enrolled; retention of existing participants through completion of the 5 year follow-up period is therefore critical. Enrollment and follow-up activities are continuing in the FS-ZONE futility trial. During the remaining years o NET-PD support. Clinical Sites may be deactivated or placed in a follow-up mode with budget reduction, depending on performance and protection of human subjects.